• Journal of Sericultural and Entomological Science
• /
• v.44 no.1
• /
• pp.22-27
• /
• 2002

The Yongcheonppong was cultured in the form of a dense mulberry field coverd with polyethylene film and was tested in Suwon and Chunchon. The agronomic characteristic and some consideration on the result of the silkworm rearing were as follows. The Yongcheonppong was the medium budding variety and was longer in length of young shoots than the Kaeryangppong. The Yongcheonppong was higher in leaf yield in spring than the Kaeryangppong and was lower in leaf yield in autumn than the Kaeryangppong to the contrary. The Yongcheonppong was a little higher in the number of branches and was longer in the length of the branch than the Kaeryangppong and so was appropriate for rearing with mulberry shoots. Yongcheonppong was more resistant to twig blight and die-back and was a little susceptible to dwarf disease. As the Yongcheonppong was most resistant to the freezing injury, it was appropriate for the cold region and enabled the farmers to rear some amount of silkworms every year. In Chunchon, The Yongcheonppong increased by 11% in cocoon yield than the Kaeryangppong when the freezing injury occurred 1 year out of 2 years and produced about the same as the Kaeryangppong in cocoon yield when the freezing injury occurred 1 year out of 3 years.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.2004-2006
• /
• 1996

A thermally driven polysilicon micro actuator has been fabricated using surface micromachining techniques. It consists of P-doped polysilicon as a structural layer and TEOS (tetracthylorthosilicate) as a sacrificial layer. The polysilicon was annealed for the relaxation of residual stress which is the main cause to its deformation such as bending and buckling. And the newly developed HF VPE (vapor phase etching) process was also used as an effective release method for the elimination of sacrificial TEOS layer. The thickneas of polysilicon is $2{\mu}m$ and the lengths of active and passive polysilicon cantilevers are $500{\mu}m$ and $260{\mu}m$, respectively. The actuation is incurred by die thermal expansion due to the current flow in the active polysilicon cantilever, which motion is amplified by lever mechanism. The moving distance of polysilicon micro actuator was experimentally conformed as large as $21{\mu}m$ at the input voltage level of 10V and 50Hz square wave. The actuating characteristics are investigated by simulating the phenomena of heat transfer and thermal expansion in the polysilicon layer. The displacement of actuator is analyzed to be proportional to the square of input voltage. These micro actuator technology can be utilized for the fabrication of MEMS (microelectromechanical system) such as micro relay, which requires large displacement or contact force but relatively slow response.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.35 no.2
• /
• pp.319-323
• /
• 2008

Edward's syndrome is a genetic disorder of 18th chromosomal trisomy. Main clinical features of this syndrome include systemic conditions, such as mental retardation, growth retardation, dyspnea, congenital heart disease, and orthopedic disorders, such as flexion deformity and rocker-bottom feet. The characteristics of fetal abnormality are hydramnios, small placenta, common umbilical artery. Infants with Edward's syndrome have very low survival rate. Almost half of them die during fetal stage. Fifty percent of them survive 2 months, and 5 to 10 percent of them survive about 1 year. A 3-year and 7 month old girl visited our dental hospital for the treatment of dental caries. Considering her systemic disease, low body weight, medical history of cardiac surgery, and difficulty in airway management, dental procedure was performed under general anesthesia. We report this case with review of literatures.

• Journal of the Korean Society of Safety
• /
• v.32 no.5
• /
• pp.157-167
• /
• 2017

Millions of People die every year from diseases caused by exposure to outdoor air pollution. Especially, one of the most severe types of air pollution is fine particulate matter (PM10, PM2.5). South Korea also has been suffered from severe PM. This paper analyzes regional risks induced by PM10 and PM2.5 that have affected domestic area of Korea during 2014~2016.3Q. We investigated daily maxima of PM10 and PM2.5 data observed on 284 stations in South Korea, and found extremely high outlier. We employed extreme value distributions to fit the PM10 and PM2.5 data, but a single distribution did not fit the data well. For theses reasons, we implemented extreme mixture models such as the generalized Pareto distribution(GPD) with the normal, the gamma, the Weibull and the log-normal, respectively. Next, we divided the whole area into 16 regions and analyzed characteristics of PM risks by developing the FN-curves. Finally, we estimated 1-month, 1-quater, half year, 1-year and 3-years period return levels, respectively. The severity rankings of PM10 and PM2.5 concentration turned out to be different from region to region. The capital area revealed the worst PM risk in all seasons. The reason for high PM risk even in the yellow dust free season (Jun. ~ Sep.) can be inferred from the concentration of factories in this area. Gwangju showed the highest return level of PM2.5, even if the return level of PM10 was relatively low. This phenomenon implies that we should investigate chemical mechanisms for making PM2.5 in the vicinity of Gwangju area. On the other hand, Gyeongbuk and Ulsan exposed relatively high PM10 risk and low PM2.5 risk. This indicates that the management policy of PM risk in the west side should be different from that in the east side. The results of this research may provide insights for managing regional risks induced by PM10 and PM2.5 in South Korea.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.12
• /
• pp.1373-1377
• /
• 2014

Hot-stamping is a method of obtaining ultrahigh-strength steel by simultaneously forming and cooling boron steel in a press die after it has been heated at $900^{\circ}C$ or above. After heat treatment, boron steel has a strength of 1500 MPa or more. This material ensures a high level of quality because it overcomes the spring-back phenomenon, which is a problem associated with high-strength steel materials, and the degree of dimensional precision is improved by 90 or more because of the good formability compared with existing types of steel. In this study, the welding characteristics were identified through the butt and lap welding of hot-stamped steel using a disk laser. Full penetration was obtained at a faster speed with butt welding compared to lap welding, and a white band was observed in every specimen.

• Research in Plant Disease
• /
• v.8 no.1
• /
• pp.66-69
• /
• 2002

In February of 2002, the gray mold disease occurred severely on primular(primular spp.) grown in a flower nursery farm in Jinju, Korea. At first, the infected leaves were discolored to gray or dark from the tip and gradually expanded to die. The fungus attacked not only leaves but petals, calyx flower stalk and stems. Conidia of the fungus in mass were hyaline or gray, 1-celled, mostly ellipsoid or ovoid and sized 6.8~16.9$\times$4.6~12.4 $\mu$m. Conidiophores were wide of 15.9~31.6$\mu$m in size. The sclerotia were readily formed potato-dextrose agar and optimum temperature far sclerotial formation was 2$0^{\circ}C$. Pathogenecity of the causal organism was and preyed according to Koch\`s postulate. The causal organism was identified as Botrytis cinerea based on mycological characteristics. This is the first report on gray mold of primula caused by Botrytis cinerea in Korea.

• 한국금형공학회:학술대회논문집
• /
• 2008.06a
• /
• pp.39-44
• /
• 2008

Magnesium alloys have given high attention to the industry of light-weigh as automobile and electronics with aluminium, titanium and composite alloys due to their high strength, low specific density and good damping characteristics. But the magnesium contained structures under high temperature have the problems related to creep deformation and rupture life, which is a reason of developing the new material against creep deformation to use them safely. The purpose of this study is to predict the creep deformation mechanism and rupture time of AZ31 magnesium alloy. For this, creep tests of AZ31 magnesium alloy were done under constant creep load and temperature with the equipment including automatic temperature controller with acquisition computer. The apparent activation energy Qc and the applied stress exponent n, rupture life have been determined during creep of AZ31 Mg alloy over the temperature range of $150^{\circ}C$ to $300^{\circ}C$. In order to investigate the creep behavior. Constant load creep tests were carried out in the equipment including automatic temperature controller, whose data are sent to computer. At around the temperature of $150^{\circ}C{\sim}300^{\circ}C$ the creep behavior obeyed a simple power-law relating steady state creep rate to applied stress and the activation energy for the creep deformation was nearly equal and a little low, respectively, to that of the self diffusion of Mg alloy.

• Korean journal of applied entomology
• /
• v.41 no.4
• /
• pp.279-284
• /
• 2002

Flacherie symptom was found in the fifth instar larvae of silkworm, Bombyx mori. The bacterial pathogen was isolated from the hemolymph of the infected silkworm and identified. The isolated bacteria caused a significant flacherie pathogenicity to the fifth instar larvae of B. mori when $5{\times}10^{6}$ cfu (colony-forming unit) of the bacteria was injected into each larva. The infected larvae began to die at 6 days after injection and resulted in complete mortality at 10 days. The bacterium was identified as Staphylococcus gallinarum based on the morphological and physiological characteristics described in Bergey's manual. This identification was further supported by the characters of carbohydrate utility analyzed from a bacterial identification system ($MicroLog^{\circledR}$) and also by the molecular structure of 165-23S rDNA internal transcribed spaces. As an insecticidal action, S. gallinarum caused hemolymph septicemia by its cytotoxic effect on the hemocytes of B. mori.

• Journal of Korean Academy of Nursing
• /
• v.8 no.1
• /
• pp.85-98
• /
• 1978

This study was designed to investigate the elderly people's attitude toward death for the purpose of identifying the issues needed in the planning of health management and care activities for the aged. The total number of subjects in this study was 354 elderly people who were accommodated in house for elderly people (185) and school for elderly people (169). The scale for the attitude toward death of aged persons as an instrument of this study was mainly constructed with reference to Schneidman's attitude questioners toward death modified of adjust the Korean cultural characteristics and attitudes concerning death. Theresultsofthisstudywereasfollows: - 1. Out of total 45.8% of the respondents consider that death is a natural phenomena and ending of life. The responses on the meaning of death appeared differently : non-religions (48.1%) and oriental religions (50.3%) consider death as a natural phenomena however western religions (47.4%) consider that death is God's call. This difference was statistically significant. (x$^2$= 56.6419. df = 10. p<0.01). Respondents with a spouses (52.4%) think death is a natural phenomena opposed to respondent without spouses (33.3%). This was statistically significant. (x$^2$= 14.7134. df= 5 p<0.05). 2. Respondents in the house for aged persons (51.9%) replied. They do not wanted death because it meant a separation from their family as compared to those from school for aged persons (26.0%). 57.9% responded that they want to be told when death is confronted. 3. 51.2% of the respondents replied that the main factor to influence their attitude toward concept of death was the dying of their friends & relatives. 79.9% of respondents expressed that wished to die. The main reason for dying was economic shortage (28.3%). 4. 70.1% of the respondents want their body to be hurried while only 1.1% of the respondents want to donate their body to a medical research. 5. Over two thirds of the respondents replied that they do not believe in a life in heaven or that they will be rebirth. 6. The questioners of this study stimulated 56.8% of the respondents to feel that they should spend the leu of their life more effectively and 15.5% of the respondents felt it gave them the opportunity to think about their death seriously.

• Journal of Forest and Environmental Science
• /
• v.23 no.2
• /
• pp.93-100
• /
• 2007

This study was carried out to select the utilizable vegetations for the stabilization of slopes and river banks, landscape creation and water quality cleansing in dams, lakes and streams. In this study, 4 species were investigated for their survival and growth characteristics in the complete and partly flooding conditions with various flooding periods. The results are as followings; Acorus calamus var. angustatus showed the highest flooding tolerance based on survival rate and growth condition. Equisetum hyemale, Acorus gramineus and Salix gracilistyla followed after Acorus calamus var. angustatus in the order of flooding tolerance. Particularly, A. calamus var. angustatus and E. hyemale showed higher survival rate and grew well even when they were completely submerged in the water up to 120 days. As they were partially submerged longer, they grew better. This ascertained that they had strong flooding tolerance. When A. gramineus were completely submerged in the water, their growth was disturbed but they did not die in the complete submergence up to 120 days. A. gramineus had a small growth disturbance and showed the highest vitality of leaves among the species. Though S. gracilistyla showed somewhat low growth rate in the complete water submergence and died in 90 days, it also can grow back to normal with some changes of water level.